T. Mirtchev, OFF-RESONANT SELF-PHASE-MODULATION-INDUCED AND CROSS-PHASE-MODULATION-INDUCED MODULATION INSTABILITIES IN SINGLE-MODE RARE-EARTH-DOPED FIBER AMPLIFIERS, Journal of the Optical Society of America. B, Optical physics, 15(1), 1998, pp. 171-180
We present an analytical model of the self-and cross-phase-modulation-
induced modulation instabilities in nonlinear, dispersive, homogeneous
ly broadened, unsaturable fiber amplifiers. The rigorous treatment of
the gain dispersion and of the gain-induced, near-resonance refractive
-index dispersion permits description of the general case of arbitrary
detuning between the laser frequency and the resonance and arbitrary
bandwidth of the amplifying transition. Simple closed-form expressions
are obtained for the combined gain coefficients and, in the self-phas
e-modulation-induced case only, for the integrated gain. A qualitative
ly new modulation-instability regime of an isolated wave in the normal
group-velocity-dispersion region is described. (C) 1998 Optical Socie
ty of America.